In the past, the process of drilling laterals was interrupted by fracking the lateral just drilled. In this technique, the drilling rig would drill the main lateral through a shoe in the main bore and then drilling was shut down to perform the fracking on the lateral just drilled into the producing formation. Thereafter, that main lateral was plugged. A whipstock was set higher and a second lateral was drilled from the main bore to exit vertically and eventually enter the producing zone. After the second lateral was drilled it would be temporarily plugged and the drilling rig moved off location. A workover rig was brought on location and the plug was pulled out of the second lateral so that a sand frack in the second lateral could take place. The second lateral would be flowed or produced until depleted to the point where another rig could be brought in to pull the plug from the main lateral so as to allow the main lateral to be produced through a production string tagged into a production packer. After the main lateral was substantially depleted, the tubing to the packer in the main lateral could be perforated so that both laterals could be produced together. The problem with this method was the high cost of keeping the drilling rig around while the main lateral was fracked and plugged. Spacing the frack jobs in time also incurred incremental costs as compared to a frack job on two laterals, if the two laterals could somehow be fracked one after the other.
To address some of these cost issues a different method was devised. The main lateral was again drilled through the shoe of the main bore and lined, if required. As shown in FIG. 1, the main lateral 10 extends from main bore 12. Optionally, a liner such as perforated liner 14 could be run into lateral 10. A wireline cement bond log could be performed and thereafter a retrievable packer 16 could be run in on wireline and set. Preferably the packer 16 has a seal bore 18 to accept a whipstock 20 as shown in FIG. 2. The packer 16 also has a removable plug 19. After inserting the whipstock 20 the vertical lateral 22 is drilled off the main vertical bore 12. Lateral 22 can also optionally be lined with a liner such as perforated liner 24. The whipstock 20 is then retrieved. The packer can be cleaned out using a cleanout tool (not shown) that is delivered on drill string combined with circulation. After the cleanout tool and delivery drill pipe are removed a top packer 26 connected to a ported sub 28 is tagged into the lower packer 16 as shown in FIG. 3. After packer 26 is set, the drill pipe is removed from the well and the drilling rig is rigged down after a wellhead gate valve (not shown) is installed. A pump truck is hooked up and builds pressure to expel a plug 19 in lower packer 16. The main lateral 10 is then fracked. A shifting plug such as a dart is delivered to obstruct lateral 10 while operating the ported sub 28 to provide access to lateral 22 that is now straddled between packers 16 and 26. Pressure on the seated plug shifts the ported sub 28 to open the access to lateral 22. Lateral 22 is now fracked and the well is shut in and the fracking equipment is moved off site. A wireline lubricator is mounted on the wellhead and the plug previously delivered to operate the ported sub 28 is retrieved with known fishing tools. At this point both laterals can be produced through packer 26 either right up the casing, if local laws permit, or through production tubing (not shown) that is tagged into packer 26. The full layout of the producing assembly, without production tubing, is shown in FIG. 4.
There were issues with this procedure mainly stemming from the fact that the lateral 22 had to go vertically through other formations before reaching the producing zone where lateral 10 was disposed. In the vertical run there could be unconsolidated zones or zone that produced water, forcing complex and costly completion procedures before lateral 22 could be produced. These expenses are avoided by the present invention that allows additional lateral exits to be coplanar with the main lateral. As will be described below, one or more laterals can be made from a main lateral already in the producing zone. The laterals can all be drilled with a drilling rig that is then removed and the laterals can then be sequentially fracked. Thereafter, the laterals can be produced together, if desired. These and other advantages of the present invention will be more apparent to those skilled in the art from a review of the description of the preferred embodiment, the drawings and the claims below, which define the scope of the invention.